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Stellite alloys are a range of cobalt-chrome designed for wear resistance. "Stellite" is also a registered trademark of Kennametal and is used in association with cobalt-chromium alloys.
Stellite alloys display outstanding hardness and toughness, and are also usually very resistant to corrosion. Typically, a part produced with a Stellite alloy is precisely cast so that only minimal machining is necessary. Due to the very high hardness many Stellite alloys are primarily machined by grinding machine, as cutting operations in some alloys cause significant tool wear even with Tungsten carbide inserts. Stellite alloys also tend to have extremely high due to the cobalt and chromium content.
The first third of the M2HB machine gun and M60 machine gun barrels (starting from the chamber) are lined with a Stellite alloy. The locking lugs and shoulders of Voere Titan II rifles also include a Stellite alloy. In the early 1980s, experiments were done in the United Kingdom to make artificial hip joints and other bone replacements out of precision-cast Stellite alloys. Stellite alloys are also used for making the cast structure of dental prostheses.
Stellite alloys have also been used in the manufacture of tool bit for lathes. With the introduction and improvements in it is not used as often, but it was found to have superior cutting properties compared to the early carbon steel tools and even some high-speed steel tools, especially against difficult materials such as stainless steel. Care was needed in grinding the blanks and these were marked at one end to show the correct orientation, without which the cutting edge could chip prematurely.
While Stellite alloys remain the material of choice for certain internal parts in industrial process valves (valve seat hardfacing), cobalt alloys have been discouraged in Nuclear power. In piping that can communicate with the reactor, tiny amounts could be released into the process fluid and eventually enter the reactor. There the cobalt would be activated by the neutron flux in the reactor and become cobalt-60, a Radionuclide with a five-year half life that releases very energetic . This phenomenon is more problematic in boiling water reactor (BWR) plants, since the steam is in direct contact with both the reactor and the steam turbine. Pressurized water reactor (PWR) designs are less susceptible. While not a hazard to the general public, about a third to a half of nuclear worker exposures to radiation could be traced to reactor components made of cobalt alloys (or stainless steel with trace amounts of cobalt in it).
Stellite alloys have also used as the cage material for the first commercially available artificial heart valve, the Starr-Edwards caged-ball valve, first implanted in 1960.
Stellite is used in pumps for components like impeller, wear rings, and shafts. Additionally, due to its strength retention at high temperatures, it is employed in power generation, chemical processing, and the food and pharmaceutical industries.
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